Forum: HoseHeads Sprint Car General Forum (go)
Moderators: dirtonly  /  dmantx  /  hosehead

Member of this message board since 1997

Dirtybeer - in theory I like your thought. However, I don't think it would work for 2 reasons. 1. Torsion bars are hardened spring steel. Welding anything to a torsion bar will quickly break loose due to the properties of spring steel. The extreme heat caused by welding (if done after the hardening process) will cause the spring rate of the bar to be ruined. 2. Even if manufacturers hardened the bars after a tab was welded in place; torsion bars are hollow and designed to twist. As the bar twists, the diameter of the bar changes slightly. They also bend inside the torsion tube of the chassis (check out any used torsion bar and you'll see scuff marks where it rubs the inner wall of the chassis tube). This act of physics would cause anything welded inside the tube to break loose rather quickly.

What I believe is causing the problem is when the person installing the torsion bar doesn't leave adequate space between the stop and the chassis tube. When I raced, our rule of thumb was you should be able to put a nickel in between the stop and the chassis tube. Reason - as the torsion bar twists, the length of the bar will get shorter. The more it twists, the shorter the bar will become. If your crew chief doesn't compensate for this, the stop will have so much pressure against it, it can literally be pushed off the end of the bar. If that moment is when the car enters the corner all hell can break loose, as we've seen recently. It is this understanding of the way a torsion bar works that I attribute to our team never having a stop fall off in 15 years of driving sprints.

That said, fewer and fewer teams these days actually understand the physics of how a chassis works. More and more teams these days are simply "wallet racing" (deep I might add) and buy parts but don't really understand what they do or why they need to do certain things. For this reason, I agree a change needs to be made to prevent anyone else from losing a life or suffering a serious injury.

My personal favorite so far is to require torsion bar companies to build them just a bit longer (quarter inch or so), machine a snap-ring groove in the end and have pit stewards check for snap rings in the staging area before any car is allowed on the track. I also agree with the person who suggested doing away with aluminum stops. Although I have a feeling Larson and most top teams are utilizing titanium stops which are just as strong as steel, if not stronger.

I'm not too keen on a snap ring because you'll need another tool to change bars. What they can do is lengthen the bar and drill it for a rue clip or something similar, no extra tools needed and I think they'd be more than strong enough to hold on a stop.

I noticed KKR was using the snap rings on the end torsion bars. Must be using the Schroeder torsion bars.

just my opinion.

you say the bar twist or wrap is pushing the stop off. well in my opinion the bar would have to shrink a heck of a lot to push the stop all the way off. even if you put the stop and the arm tight against the tube the bar twist should only push the arm or stop the small distance the bar shrinks, not push it all the way off. and why doesn't it push both the arm and the stop?

also most of the incidents i have heard of stops coming off are on the RF which gets the least bar wrap of all the bars on the car. if it is bar wrap that is pushing off stops, then why aren't LF and LR stops the ones coming off?

it has been said that the RF stop gets hammered off because it spends so much time unloaded and slaps around in the tube and eventually knocks the stop off.

also why does it seem like we are seeing more of this type of thing recently? i don't recall hearing much of this sort of thing happening years ago.

when we installed stops and arms we always made sure there was enough of a pinch gap in the arm or stop that it would securely clamp onto the bar before it bottomed out on itself. we always made sure there was still just a small pinch gap in the arm or stop when torqued down on the bar. we also always made sure we were not thread binding the clamp bolt.

we never have had a problem with a stop or arm coming off under normal use.

we also never used TI stops on the front that i remember.

to indy and beyond!!

Both the 13 and the 1k know how to install a torsion bar/stop. I also think it's safe to say that they both use Ti stops. My guess is both teams utilize either the same stops and or the same bars.

I would like to hear from both teams... I would like to know what brand bar and what brand stop was in place when the accidents occurred.

I don't think this is an unfair request given the seriousness of this issue. I hope that the race teams have the courage to speak out!

run coilover shoxs

Either that or we could actually figure out why the stops are falling off...

I appreciate your reply buzz, I like a healthy debate. I agree with what you said, just don't think I explained myself very well after reading it again.

I can't explain why the RF has gotten all the attention as the RF and LF can both have potential. RR and LR are almost always in a loaded state if the driver can remain on the throttle and smooth. As the car goes down the straight, weight is transferred to the rear, the front bars unload. However, depending on each cars setup, the amount it unloads can be different. Typically the RF shock will top out before the bar fully unloads (that's why the RF corner lifts off the ground at the end of the chute). Test this by having your largest friend stand on the LR corner hard enough to get the RF to raise in the air. Now try to lift the RF torsion arm off the axle. Trust me, there is pressure on that torsion stop and arm even though its up in the air.

Now if the driver has to quickly get off the throttle, the RF & LF bar goes from 'unloaded' to an extreme loaded state. Or, an ill handling car that is getting too hard on the right front from apex to exit of the corner can also be a culprit.

As for my theory of the arm being pushed off, I never meant to imply it was being pushed off in one fell swoop the full width of a stop. It is slowly getting tagged lap after lap. And once the stop begins to slip off the bar, every fraction of an inch it continues to get looser and looser. Over my 15 years driving sprints I recall several instances of stops AND arms falling off competitors cars. I don't recall if they were always the RF though.

Hell, maybe there's no merit at all to my opinion....I feel smarter though....I did stay at a Holiday Inn Express last week.... All kidding aside, someone with more brains than me should dig into this and figure it out before anyone else is hurt.

Member of this message board since 1997

An excellent suggestion....

In aus Ti stops are banned on the front of the car, but people use them anyway, most use ally stops.

i've only ever herd of stops coming off brand new torsion bars, but thats over here.

We dont have the big 1/2 mile or high banking tracks either

I don't believe it would effect the performance of the bar,as the twist should occur in the middle of the bar and not the ends.Whatever the best solution is,I hope it comes about soon.Like you,I also mentioned in the last discussion on this problem that it could well be happening from not enough end play being used and the bars pulling out of the stops.

Guys and Gals,

The 13 and the 1k don't run worn out junk... they also understand how to properly install a trosion bar/stop.

The ideas for improvement are fine, but I wanna know what the f*^k is going on! There's a problem with either the bar and or the stop, or maybe both. I wanna know what it is, so we can stop destroying race cars.

I'm frustrated with the people in the know. I'm talking specifically about the teams and the manufacturers involved. I wish someone had the courage to speak out. Someone knows exactly what's happening and it's time to put a stop to the madness, the wrecked cars, the injuries, the ...

On the 13 car we use Schroeder bars and are in the process of getting some with a snap-ring groove. Also looking to tether the front axle with something like a drag link strap.

Is it possible that the load that the bar is putting on the stop is trying to force the stop to open up at the split. If this happens it could loosen up the stop or arm due to working the splines or pulling on the threads on the bolt and nut. If anybody runs aluminum nuts still this would really streach the threads and cause the bolt to loosen. With the new shock packages that are being run ( hold downs ) there is a lot more pressure on the left front arm and stop. If the stop was to lossen even slightly it would work itself off of the bar due to the loading and unloading affect.

85,

Thank you for sharing... I know your team has been through a lot!

What brand stops are you using? Are they aluminum or titanium? Any other insight into a possible cause?